Clayton Kershaw: Historically Platoon-Proof


To put into perspective everything that Clayton Kershaw means to the game of baseball, both from a historical and current standpoint, is an impossibly difficult task to undertake. The 26-year-old southpaw trotted onto the fresh-cut grass at Camelback Ranch-Glendale last Thursday as the reigning National League Most Valuable Player, a three-time Cy Young Award winner and owner of four consecutive ERA titles, to make no mention of the seven-year, $215 million extension he signed last winter that made him the wealthiest pitcher in the history of baseball. Whether it be the numbers or financial figures, Kershaw has undoubtedly staked his claim amongst the game’s most influential and historic hurlers.

But have we paused long enough to consider what’s made Kershaw as historically dominant as he’s become, especially last season, during which he was at his best? No doubt, Dodgers amateur scouts knew Kershaw had the projection of a future superstar when they plucked him with the seventh overall pick in 2006. But his path to dominance has been one filled with highs and lows, struggle and triumph, ridiculousness and absurdity. The lowest point of Kershaw’s career probably transpired at the very beginning of it, posting a 4.26 ERA and strikeout to walk ratio of 1.92 as a 20-year-old rook in 2008. Last season, he authored a career-low 1.77 ERA and 7.71 K/BB over 27 starts. What’s helped him get to this point?


Kershaw’s K-BB% platoon splits reached a point of equilibrium in 2014, one we’d never before seen from the Cooperstown-bound southpaw.

One of the more interesting things I’ve found through my research can be seen in the graph above, which illustrates the year-by-year differential between Kershaw’s strikeout rate and walk rate against same and opposite-handed batters over the course of his career. As we can distinguish with ease, Kershaw struggled against right-handed batters in this respect early on, posting a differential of only 6.7% combined between the 2008 and 2009 regular seasons. But after an ’09 campaign that saw him take steps forward in several respects, Kershaw began to close the books on that K-BB% differential, effectively becoming a more balanced and platoon-proof starter; his K-BB% to righties from 2010 to 2013 increased to 16.4%, quite the improvement.

But what catches the eye in this graph is that which Kershaw managed to accomplish last season, insofar as this differential. For the first time in his career, the first time in a career that has long been considered historic in the eyes of many, Kershaw’s K-BB% against righties and lefties mirrored one another, reaching somewhat of a state of equilibrium. And it’s statistically true: Kershaw’s K-BB% against righties rose to a career-high 27.7% in 2014, a near match to 28.0% against left-handed batters. What’s remarkable about that number is its context in recent history. No ERA-title qualifying left-handed starter has accumulated a higher K-BB% differential versus right-handed batters in a single season since Randy Johnson (32.1%) in 2001.

Interpreting these improvements and comprehending their place in baseball history is one thing, but what we really want to know is how Kershaw was able to bring his K-BB% against righties up to par with his numbers against left-handed batters last season, especially given his long-standing issues with opposite-handed batters prior to 2014. Knowing this will give us a better understanding of and appreciation for Kershaw’s craft on the mound, and may even offer some guidance as to whether we can expect him to increase his strikeout totals next season and into the foreseeable future. At the very least, it could give us something specific to watch for in his outings this spring.


Data courtesy TruMedia Networks

How is it that Kershaw became so historically platoon-proof last season? Easy: He changed his approach to one that keys on establishing the inside corner. Overall, no qualifying starter in 2014 located more of his offerings to the inside part of the plate than Kershaw, who located a career-high 44.0% of his offerings there. Compared to the next-closest guy on the list (Jon Lester, 39.7%) and the league-average pitcher’s frequency (27.9%), that number is obscenely high. It wasn’t always this way. As a rookie in 2008, Kershaw threw just 29.3% of his pitches to the inner third, much closer to the average pitcher, and from 2009 to 2013 located 37.5% of them to the inner-third of the plate. If we’ve learned anything here, establishing the inside corner has now become a critical element to Kershaw’s approach within the strike zone.

But this change in scheme can mainly be attributed to right-handed hitters, against whom Kershaw has increasingly challenged at the inner-third since breaking onto the scene seven years ago. The graph and table above give us a nice display of this altered approach over time, and the results that have followed in consequence. In 2008, Kershaw threw roughly one in three (32.1% to be exact) of his pitches ‘inside’ on a given right-handed batter. That number has since risen to one in two (50.7%) last season, which is a considerable increase and one that has triggered more swings, misses, and ground balls from right-handed batters. His approach to left-handed hitters hasn’t altered much, locating about 20% of his offerings ‘inside’ on lefties each season. This tells us Kershaw’s change in approach to righties have been calculated and deliberate; to become an elite starter, he realized change was necessary against opposite-handed batters.



The pitch most responsible for Kershaw’s new-found approach over the years is the same one that made him historically platoon-proof last season: The slider. Last season, Kershaw located his slider exceptionally well against right-handed hitters, pinpointing the low-and-inside portion of the zone, which is shown in the second image above. Overall, 57.0% of his sliders were located ‘inside’ on righties, up from 43.5% in 2010. The result: More swings, more misses, and more ground balls. Right-handed batters offered at 67.0% of his sliders last season, up from just 44.4% in 2010. They missed on 48.2% of those swings, up from 41.6% in 2010. And their ground-ball rate against the pitch soared to 50.0% last season, a healthy increase from 34.5% five years ago.

It’s difficult to think back on a time when Clayton Kershaw struggled in any capacity, but he certainly did as a rookie in 2008. Fresh off a minor league stint in which he struck out nearly 12 batters per nine innings, the young 20-year-old seemed unable to keep major-league hitters in check. But as time has progressed, so has Kershaw’s willingness to adjust. Not only has he steadily implemented the slider into his arsenal, but he’s also learned to command it to the inner portion of the plate exceptionally well, so much so that it’s helped eliminate a burdensome platoon split against right-handed batters. So the next time you see Kershaw on the mound against a right-handed hitter this spring, you’ll know how he intends on attacking him: Down-and-inside, with that filthy slider.


Statistics courtesy of TruMedia Networks LLC and FanGraphs

Alec Dopp is a contributor to Gammons Daily and is a former scouting intern with Perfect Game USA. Connect with him on LinkedIn and give him a follow on Twitter @AlecDopp, if you’d like.